Maharashtra Board Class 12 Chemistry Important Questions 2027 (Repeated in Board Exams)

When gold crystallizes, it forms face-centered cubic cells. The unit cell edge length is 4x10-8 cm. Calculate the density of gold. Molar mass of gold is 197 g mol-1.

(i) Define: (a) Schottky defect (b) Ferromagnetism (ii) Write the name of catalyst used in preparation of HDP. (iii) Draw structure of isoprene unit of natural rubber.

The relation between edge length and radius for body centered cubic structure is: (a) r=a/2 (b) r=sqrt(3)a/4 (c) r=sqrt(2)a/4 (d) r=sqrt(3)a/2

(a) Derive a relationship between molar mass, density of the substance and unit cell edge length. (b) Define - paramagnetic solids.

(a) Distinguish between crystalline and amorphous solids. (b) Explain bleaching action of chlorine in the presence of moisture.

Coordination number of atoms in bcc crystal lattice is _____. (a) 2 (b) 4 (c) 6 (d) 8

(a) State Raoult's law. (b) Derive the relationship to determine molar mass of non volatile solute by depression of freezing point.

Define the following terms: (a) Isotonic solution (b) Colligative properties

Unit of Henry's constant is _____. (a) mol L-1 bar-1 (b) mol L bar (c) mol L-1 bar (d) mol-1 L-1 bar-1

(a) 0.01 m aqueous formic acid solution freezes at -0.021 C. Calculate its degree of dissociation. (Kf = 1.86 K kg mol-1) (b) Write properties of interstitial compounds.

A mixture of benzene and toluene contains 30% by mass of toluene. At 30 C, vapour pressure of pure toluene is 36.7 mmHg and that of pure benzene is 118.2 mmHg. Assuming ideal solution, calculate partial pressure of each constituent in the above solution at 30 C.

Henry's constant for CH3Br(g) is 0.159 mol dm-3 bar-1 at 25 C. Calculate its solubility in water at 25 C, if its partial pressure is 0.164 bar.

(i) Define: Common ion effect. (ii) Write preparation of glucose from starch.

The pOH of 0.01 M HCl solution is _____. (a) 1 (b) 2 (c) 11 (d) 12

A solution has hydrogen ion concentration 0.01M. Calculate pOH of the same solution.

(i) Acetic acid is 5% ionised in its decimolar solution. Calculate the dissociation constant of acetic acid. (ii) Write chemical formula of epsom salt. Give two uses of H2SO4.

Derive Ostwald's dilution law equation for a weak acid.

The pH of buffer solution containing 0.05 mol NaF per litre and 0.01 mol HF per litre (pKa=3.1427) is ____. (a) 3.8417 (b) 3.1427 (c) 0.3841 (d) 0.0384

When 6.0g of O2 reacts with ClF as per 2ClF(g)+O2(g)->Cl2O(g)+OF2(g), the enthalpy change is 38.55 kJ. Calculate the standard enthalpy of the reaction.

(a) Derive relationship between dH and dU for a gaseous chemical reaction. (b) Give reason - Ozone is a good bleaching agent. (c) Write any two uses of SO2.

Define the following terms: (a) Intensive property (b) Standard enthalpy of combustion

Ideal gas expands isothermally from 20 dm3 to 25 dm3 at constant pressure of 1.5 bar; then work done in dm3 bar will be _____. (a) -1.5 (b) -5 (c) -7.00 (d) -7.5

Write the mathematical equation of first law of thermodynamics for following processes: (a) Isochoric process (b) Adiabatic process

Calculate maximum work done when 32 g of oxygen expanded isothermally and reversibly from pressure 2 bar to 1 bar at 298 K.

Calculate change over temperature for a certain reaction, whose dH0 is -60 kJ and dS0 is -150 JK-1.

(a) State second law of thermodynamics. (b) Define - Nucleotides. (c) Write chemical reaction for conversion of benzene diazonium chloride into benzene.

How many coulombs of electricity is required to produce 1g of sodium metal by reduction of sodium ion?

(a) Write cell reactions of hydrogen-oxygen fuel cell at anode and cathode. (b) Write an application of electrochemical series.

Write the relation between conductivity and molar conductivity.

The standard potential of electrode Cu++ (0.02 M) | Cu(s) is 0.337 volt. Calculate its potential in volt.

Write the SI unit of cell constant.

(a) Draw neat and labelled diagram of standard hydrogen electrode. (b) Calculate e.m.f. of the given cell using standard electrode potentials.

Calculate the standard potential of the following cell at 25 C:

The unit of rate constant is per second, the order of reaction is: (a) Zero (b) First (c) Second (d) Third

Derive the relation between half life and rate constant for a first order reaction.

In first order reaction 60% of reactant decomposes in 40 min. Calculate the rate constant of the reaction.

Distinguish between order and molecularity of a reaction.

What is zero order reaction? Derive integrated rate law equation for zero order reaction.

Integrated rate law equation for a zero order reaction is: (a) k=(2.303/t)log([A]0/[A]t) (b) [A]t=[A]0-kt (c) k=t/[A] (d) [A]0=[A]t/kt

(a) Explain anomalous behaviour of oxygen with respect to (i) Atomicity (ii) Magnetic property (iii) Oxidation state (iv) Nature of hydride (b) Write any two uses of helium.

The shape of bromine penta-fluoride is _____. (a) Linear (b) Bent-T-Shape (c) Tetrahedral (d) Square pyramidal

Draw the structure of perchloric acid.

Write the name of product obtained, when selenium is treated with magnesium metal.

Explain the trends in the following properties of group 17 elements: (i) Atomic radii (ii) Electronegativity

(i) Write observed electronic configuration of chromium (Z=24). (ii) Calculate magnetic moment of Ti3+ by using spin only formula (Z of Ti=22). (iii) Define Green chemistry.

(a) Write chemical reactions taking place during extraction of iron in zone of reduction of the blast furnace. (b) Write observed electronic configuration of gadolinium. (Z=64)

(a) Write general electronic configuration of 3d series elements. (b) Write any two points which explain about the colour of a transition metal ion.

Write two similarities and two differences between lanthanoids and actinoids.

Write the names of the metal elements in brass alloy.

Write the name of radioactive element in lanthanide series.

The compounds of Ti4+ ions are colourless due to ......

Define Lanthanide contraction. Write the balanced chemical equations when acidified K2Cr2O7 reacts with H2S.

(a) Write the representation of sodium hexacyanoferrate (III). (b) Write type of hybridization and magnetic behaviour of: (i) [Co(NH3)6]3+ (ii) [NiCl4]2-

(a) Define: (i) Co-ordination numbers (ii) Ambidentate ligand (b) Write a note on Clemmensen reduction of propanone.

The correct structure of complex having IUPAC name sodium hexanitrocobaltate (III) is (a) Na3[Co(NO2)5] (b) Na4[Co(NO2)6] (c) Na3[Co(NO2)6] (d) Na4[Co(NO2)5]

Write the oxidation state of Nickel in [Ni(Cl)4]2- complex ion.

(i) Calculate effective atomic number of Fe2+ in [Fe(CN)6]4- [Z=26]. (ii) Draw neat and labelled diagram of lead accumulator. (iii) Write two advantages of hydrogen-oxygen fuel cell.

(i) Write the postulates of Werner's theory of co-ordination complexes. (ii) What is the action of ethane-1,2-diol on acetone?

(a) Explain the formation of [CoF6]3- complex ion with respect to (i) Oxidation State of Cobalt (ii) Type of hybridisation (iii) Magnetic property (iv) Geometrical shape (b) Write the name of ligand used to estimate hardness of water.

Write IUPAC names of following co-ordination ion / compound: (i) [Cu(NH3)4]2+ (ii) Na3[AlF6]

Explain ionization isomers with suitable example in complexes.

The co-ordination complex ions [Co(NH3)5(NO2)]2+ and [Co(NH3)5(ONO)]2+ are _____ of each other. (a) ionization isomers (b) solvate isomers (c) linkage isomers (d) co-ordination isomers

Explain Homoleptic and Heteroleptic complexes with example.

(a) What is the action of following reagents on Bromoethane? (i) KNO2 (ii) 'Mg' metal (iii) Silver acetate (b) Draw structure - DDT insecticide.

(i) Convert ethanoic acid to ethanol. (ii) Explain the mechanism of alkaline hydrolysis of bromomethane.

Complete the following reactions: (i) CH3-CH=CH2 + HBr -> ? (ii) C2H5OH + SOCl2 --(heat)--> ?

Among the following benzylic halide is ___. (a) aryl-X (b) C6H5-CH2-X (c) vinyl-X (d) CH3 substituted aryl-X

Explain optical activity of 2-chlorobutane.

What is the action of following reagents on chlorobenzene? (i) conc. HNO3 (ii) fuming H2SO4

The metal used in preparation of Grignard reagent is _____. (a) Al (b) Mg (c) Na (d) Fe

Write preparation of (a) diethyl ether (b) ethyl cyanide from ethyl bromide.

Anisole reacts with HI at 398K to form: (a) cyclohexanol (b) benzenol (c) iodobenzene (d) benzene

Convert the following: (a) Ethanol to ethoxyethane (b) Phenol to p-benzoquinone (c) Salicylic acid to aspirin

Convert the following: (i) Ethanol into sodium ethoxide (ii) Phenol into o-phenol sulfonic acid (iii) Bromomethane into methoxyethane.

Write chemical reactions for the preparation of phenol from isopropyl benzene.

Explain aldol condensation reaction with respect to ethanal.

Explain Cannizzaro reaction with suitable example.

The reagent used to convert acetyl chloride to acetaldehyde is: (a) SnCl2 + HCl (b) Zn-Hg + Conc.HCl (c) NH2-NH2/KOH,glycol (d) H2/Pd-BaSO4

Convert the following: (a) Acetic acid to ethyl alcohol (b) Acetic acid to acetic anhydride (c) Acetyl chloride to acetamide

Write the IUPAC name of the given structure (2-hydroxybenzaldehyde / salicylaldehyde).

Write the reagents used for the reduction of carbonyl group in Clemmensen's reduction.

(i) Draw the structure of 2,4-dinitrophenylhydrazone of acetaldehyde. (ii) The rate of A+B->? is 3.6x10-2 mol/dm3/s when [A]=0.2 M and [B]=0.1 M. Calculate the rate constant if reaction is first order in B and second order in A.

Write a note on Haloform reaction.

The product of the following reaction is C2H5-CO-CH3 (pentan-2-one) on reduction: (a) CH3-CH2-CH2-CH2-OH (b) CH3-CH(OH)-CH2-CH3 (c) CH3-CH2-CH2-CH3 (d) CH3-CH2-CH2-COOH

What is the action of following reagents on ethyl amine? (Indicate by reaction) (a) Nitrous acid (b) Chloroform and KOH

(i) Convert acetamide into ethyl amine. (ii) Explain amphoteric nature of water.

Preparation of ethanamine from acetonitrile represents: (a) Gabriel phthalimide synthesis (b) Mendius reduction (c) Hofmann hypobromite degradation (d) Sandmeyer reaction

The correct order for basic strength of amines and ammonia is _____. (four orders given involving NH3, RNH2, R2NH, R3N)

(i) What is peptide linkage? (ii) Write general characteristics of interhalogen compounds.

Write the glycosidic linkage present in maltose.

Write preparation of glucose from sucrose.

(i) Write a reaction for preparation of Nylon-6. (ii) The salt of Sc3+ ion is colourless and the salt of Mn3+ ion is coloured. Explain. [Z of Sc=21 and Z of Mn=25]

Write the chemical name of Teflon.

Write reactions involved during preparation of Nylon 6,6 fibre.

Write the IUPAC name of isoprene.

Mention the types of polymers formed on the basis of intermolecular forces. Write any two uses of low density polyethylene.

(a) Mention the names of four principles of green chemistry. (b) Write advantages of nanoparticles and nanotechnology in the field of energy sector.

(i) Write the formula to measure % atom economy according to green chemistry. (ii) Convert: (a) Benzene into benzaldehyde (b) Cyclohexene into adipic acid.

Write the name of nanoparticle which acts as highly effective bacterial disinfectant.

(i) Write example of one dimensional nanostructure of size less than 100 nm. (ii) Write the hydrolysis reaction of ethyl methyl ether.